It has, since the ancient years, considered being a strategic location. On the east side lie the ruins of a great Byzantine - Venetian Castle. During the Middle Ages, the island served as a refuge for Albanian settlers' animals.
Dokos, according to archaeological studies, has been inhabited since the era of copper, 6000 BC. In 1975, Peter Throckmorton discovered a wreck near Dokos that has been dated to about 2150 BC, and maybe the oldest shipwreck known.
Source: wikipedia.org